A brace of tries from full-back Dan Evans plus further scores for Jeff Hassler, Rhys Webb and Dan Baker gave the Welsh side a handsome win, fly-half Dan Biggar added 17 points with the boot.
Treviso did at least manage to get themselves on the board with a late try from wing Ludovico Nitoglia, converted by Joe Carlisle, as they look towards their clash with Racing Metro 92.
The only blow for the Ospreys was an apparent neck injury suffered by No 8 Baker, which required lengthy treatment before the Wales international was stretchered off.
The result made it seven wins from seven for the Ospreys so far this season, they are the only unbeaten side in Europe, and sets them up for next weekend’s meeting with Northampton Saints at Franklin’s Gardens.
The home side were on the front foot from the off and Biggar quickly had them nine points to the good with three successful penalties.
The opening try came in the 22nd minute. A powerful scrum shove opened up space on the left where Evans broke the first line of defence, and Treviso’s scramble defence could not prevent Biggar’s short pass putting Hassler over.
Treviso thought they had a way back into the game when wing Ludovico Nitoglia raced over from Joe Carlisle’s half-break, but the score was ruled out for a forward pass.
Matters got worse for the visitors when replacement lock Marco Fuser saw yellow for illegally stopping a powerful Ospreys maul, and the hosts made the most of the numerical advantage as in-form scrum-half Webb burrowed over for his sixth try in just seven games.
No sooner had Fuser returned from the sin bin, Salesi Manu was handed a 10-minute rest for also infringing in a maul.
Again the Ospreys capitalised, with Evans eventually getting the ball down as the Treviso defence desperately tried to hold him up over the line.
Baker soon brought up the bonus point as he cantered over before his afternoon was unfortunately ended by injury.
Evans got his second try after Biggar made an arcing break in midfield and Webb’s miss pass found the full-back free on the left.
But Treviso had the last word as Nitoglia scampered clear to score behind the posts.
